1. Field of the Invention
The present invention relates to a fuel usage tracking device designed to monitor the engine running times for vehicles equipped to utilize more than one type of fuel. Specifically, the fuel usage tracking device allows the user to monitor the total fuel usage and the fuel usage of each type of fuel by determining the total engine running time and the engine running times on each fuel. In an alternative embodiment, the fuel usage tracking device allows the fuel usage of each type of fuel to be monitored by measuring the total distance driven with the vehicle and the distance driven on each type of fuel. In another alternate embodiment, the device samples the ratio of the fuels being simultaneously burned by the vehicle for instantaneous and average fuel mixture information monitoring.
2. Description of the Related Art
Vehicles capable of running on two different types of fuel or "dual fuel vehicles" are known in the art. U.S. Pat. No. 4,463,735, to Stoltman, discloses a dual fuel supply system for automotive engines in which the fuel tank has been adapted to contain both methane and propane at pressures up to 17,000 kPa. Fuel is supplied to the engine from the fuel tank through a fuel metering apparatus via a switching valve and pressure regulator. The pressure inside the fuel tank governs which fuel is utilized by the engine. When the pressure of the fuel tank exceeds 1,400 kPa, the switching valve assembly directs methane through the fuel metering apparatus to the engine and when the pressure of the fuel tank is less than 1,400 kPa, then the switching valve assembly directs propane through the fuel metering apparatus to the engine. This system has an electronic control unit which is used to adjust the operation of the fuel metering apparatus to provide the fuel flow required by the engine. Even though this system is capable of switching between the two fuels, it is not equipped with a timing or a monitoring mechanism which would allow a determination of which fuel is being utilized and the duration of that use.
U.S. Pat. No. 4,603,674, issued to Tanaka, provides another example of a dual fuel engine. This device governs the speed of the engine and controls the switching between two types of fuel (gasoline and diesel fuel). This patent discloses an improvement over conventional devices by electrically switching between the diesel fuel operation mode and the gasoline fuel operation mode using a mode switching control circuit. Conventional devices effected a switch between fuels mechanically by way of a linkage mechanism. The Tanaka device is only concerned with the actual switching between the two types of fuel and fails to provide any means to determine when and how long the engine is running on each type of fuel.
U.S. Pat. No. 4,630,292 to Juracich et al. discloses a device for measuring the running time of an engine and for monitoring the usage of the engine in relation to the movement of the vehicle. The device contains timers which provide an indication of the total running time of the motor, the stationary running time of the vehicle and the in-motion running time of the vehicle. The record generated by this device is used to obtain a rebate of road taxes for fuel used while the engine is running and the vehicle is stationary. This device utilizes a first signal generator which preferably is an oil pressure switch which is activated when the oil pressure reaches a normal operating level. A second signal generator is also used which preferably is a speedometer generator coupled to the drive train of the vehicle. Although this device is capable of measuring engine running times, it does not disclose any mechanism to allow it to distinguish engine running times of the vehicle on different types of fuel. Further, it does not measure the distance traveled by the vehicle.
Although vehicles are presently available which are capable of running on different types of fuel, a problem in the alternative fuel industry is being able to substantiate the fuel usage of each type of fuel in the vehicle. Most conversions of vehicles from gasoline burning to either dual fuel or to dedicated alternative fuel usage vehicles are financed through various public and private funding grants. Because there is an insufficient alternative fuel infrastructure, and more particularly, a shortage of alternative fuel refueling stations, many vehicles which have been converted to dual fuel use continue to operate in part on gasoline.
Most grants funding dual fuel vehicle conversion stipulate that the alternative fuel must be utilized approximately 80-90% of the total vehicle usage. Therefore, operation of a converted vehicle on the alternative fuel for less than this percentage does not satisfy the intent of the providers who have funded the conversion. Grant funders would like to have a verifiable method to substantiate usage other than the honor system. Therefore, there is a need for a device which can be attached to the vehicle and which can accurately verify compliance with the terms of the funding grant. There is currently no device available which can monitor which type of fuel is being burned in the engine of a dual fuel vehicle and cumulatively keep track of this usage.
The present invention provides a device which is capable of monitoring the type of fuel used or the ratio of the fuels burned by a multi-fuel vehicle. The device keeps track of the usage of each fuel type since a last reset as well as the total usage of each fuel type since the device was installed in the vehicle. For flexible fuel vehicles capable of running on a mixture of fuel types, such as gasoline and methanol, the device tracks the instantaneous and calculates the average fuel mixture ratio.